The Stovebolt Site Forums The Shop Area Engine Shop Vacum Leak at Intake Manifold

Rebuilt 216 engine with new everything on it, when started it ran poorly. I took the advice of many here on the Forum and check for a vacuum leak on the engine and found that the intake manifold apparently is the problem. I sprayed "Carb Cleaner" around the area where the manifold makes up to the engine and when I did the engine would stumble, thus indicating a leak. This manifold was reconditioned when the engine was rebuilt last year. It was warped so the mating surfaces were built up with weld and milled down to produce an even and uniform surface. A new gasket was installed and it was torqued down accordingly. In light of all this what do you recommend from this point, how can I make this manifold stop leaking and seal tight? I realize I will have to pull it off but where to from here would a double intake manifold gasket solve the leak?
The engine mating surface for the manifold was good and did not need any repair Thanks for the help I appreciate it.


God bless,


Dave

Did you install the alignment rings?

Yes, especially in that they had to be ground down when the manifold was welded and milled down to fit tightly. Thanks for your thoughts.

Dave

The work on the manifold should not have anything to do with the alignment rings. When looking at the interface between the manifold and the head, there should not be any space showing. If there is a space, it is hung up on the rings.

Dave,

If the manifold is not being held out by the alignment rings, go ahead and try two gaskets as a last resort.

The maifold at one time was hung up due to the rings and would not seal tight to the head in that the alignment rings were keeping it from seating tight. That problem was resolved, but the intake is, as I just discovered, still sucking in air.

Secondarilly and related to this, there is a seal kit for the heat riser on the exhaust side of the mainfold. Dose anyone know where I can get this kit? I tried Bowtie Bitts, Classics of America, Brothers, and Jim Carter, no luck.


Dave

fel pro 8597

your local auto parts can get it
good luck

I've heard different ideas about mounting the manifolds. What about loosening both manifolds, retightening to the block from the middle out, then tightening the intake and exhaust back together? Or a different tightening pattern?

Just spit-ballin' here . . .

-Michael

Is the heat-riser seal kit you refer to the intake-to-exhaust-manifold gasket in this kit (and is shown above by DADS50)

I hope to have the manifold off this week and to my machinest for his evalation. The kit I'm reffering to is the one where the heat riser goes through the side of the mamifold below the carburator. The heat riser that semicircular thing that moves and has a spring on it. There is a seal around the riser shaft mine leaks exhaust. Somewhere I've seen a kit to repalce that seal. As to the leak, any other ideas as to how to make it seal properly. Mike your spit balling idea is not bad.

As I mentioned above, the alignment rings can cause issues. When I did our '40 this spring the machine shop resurfaced the manifold crooked. I had to make the alignment rings off center some to allow the manifolds to fit against the head. The carburetor did sit somewhat tilted towards the valve cover. Once I had the alignment rings surfaced down so the manifold would sit flush against the head I installed the gaskets and tightened it from the center out as others have mentioned. I ended up having the carburetor spacer machined a couple degrees so the carburetor sat level. I'm still not happy with the manifolds be machined wrong but I had to live with what I had to get things going. I'll change it out at some point. It ended up working and running good. Don

Theres nothing wrong with a little Ulta Blue Gasket Maker by Prematex around the intake ring than the gasket and a little more around the ring again before installing the intake manifold I only use it when there's a problem,almost never but You have to remember that a head and manifold that are 50+ years old might have some pits in the surface ,and We all don't have the money to get machining done all the time.

Fel-Pro makes a intake gasket set that has the intake to head and the heat riser gaskets


Pete